Scriban: Sandbox escape due to TypedObjectAccessorcache bypassing MemberFilter after TemplateContext reuse

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary TemplateContext caches type accessors by Type only, but those accessors are built using the current MemberFilter and MemberRenamer. When a TemplateContext is reused and the filter is tightened for a later render, Scriban still reuses the old accessor and continues exposing members that should now be hidden. Details The relevant code path is: - TemplateContext.GetMemberAccessor() caches accessors in memberAccessors by Type in src/Scriban/TemplateContext.cs lines 850–863. - For plain .NET objects, GetMemberAccessorImpl() creates a new TypedObjectAccessor(type, keyComparer, MemberFilter, MemberRenamer) in src/Scriban/TemplateContext.cs lines 909–939. - TypedObjectAccessor stores the current filter and precomputes the exposed member set in its constructor and PrepareMembers() in src/Scriban/Runtime/Accessors/TypedObjectAccessor.cs lines 33–40 and 119–179. - Member access later goes through ScriptMemberExpression.GetValue() in…

Published by the source

24 Mar 2026, 22:11 UTC

Last modified by the source

6 Jul 2026, 13:08 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5wr9-m6jw-xx44

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# Patch Next advisory brief: GHSA-5wr9-m6jw-xx44

Advisory: Scriban: Sandbox escape due to TypedObjectAccessorcache bypassing MemberFilter after TemplateContext reuse
IDs: GHSA-5wr9-m6jw-xx44
Record: https://patchnext.com/advisories/ghsa-5wr9-m6jw-xx44 (revision 1, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: scriban.signed 7.0.0; scriban 7.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet scriban.signed: affected < 7.0.0; fixed in 7.0.0
- NuGet scriban: affected < 7.0.0; fixed in 7.0.0

## Suggested inspection (read-only)
- NuGet scriban.signed: check the installed version with your package manager.
- NuGet scriban: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on scriban.signed, scriban.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5wr9-m6jw-xx44 (GitHub-reviewed advisory GHSA-5wr9-m6jw-xx44 lists affected ranges: NuGet scriban >=0 =0 <7.0.0)

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